Resettable circuit breaker



Oct. 28, 1952 B. MILLEN RESETTABLE CIRCUIT BREAKER Filed Jan. 5 1951 INVEN TOR. 5m M/ZZf/V ATTORA/ffd Patented Oct. 28, 1952 "Ben Millen, Cleveland, Ohio Application Januaryi, 1951, Serial No. 204,523

4 Claims. 01. 175-294) Thisinvention relates to a circuit breakerof the resettable type employing ate'mperature responsivebimetalelement as the means for breaking the circuit; a f

Itis an jobject of this invention to provide a circuit breaker inthe formof a plug-in fuse which isof very simple construction and which is, therefore; capable of being manufactured very economically.

Another object of the invention resides in the provision of a circuit breaker having a push button which is depressible to reset the breaker after the thermostatic bimetal element has responded to an overload to break the circuit.

A further object of the invention resides in the provision of a circuit breaker, having a fusible element connected in series with athermos'tatic bimetal element whichlserves as .apositive circuitbreaker when thecircuit is overloaded to a predeterminedextent regardless of the condition,

of thebimetal element.

A un further object of the invention is to provide a'circuit breaker in the form .of a plug in fuse having a pair of contact points which are movable to open and close the circuit and which are designed to give relatively longservice.

In the drawings: Figure 1 is a vertical sectional view through the fuse,;j.

Figure 2 is a fragmentary the fuse body. 7 r Figure 3 is a top view of the fuse.

perspective view of Figure 4 is a detailed view showing a modified construction breaker. V a

Referring to the drawings, itwill be seen that of contact points for the circuit the fuse of this invention resembles to a great extent a fuse of conventional design in that it includes a body member 10 of insulating material which may be formed as a lower member l2 and. a cap member I4, the sides of the lower mem-.

ber 12 having threads l6 formed thereon to receive a shell member I8 which is correspondingly threaded. Bottom I2 and cap member l4 may be secured together by any suitable means as at,

20. Bottom member I2 is fashioned with a central chamber 22, at the lower end of which there is a recess 24.

A'bimetallic arm 26 is mounted in chamber 22 with its lower end seated at the, base of recess 24.

Arm26 is secured to bottom I2 by a rivet 21 which extends through an aperture 30 in member l2..

Xbushing 32 has a reducedportion 34 which separates and thereby insulates the lower end of arm 26 from rivet 21.

Rivet 21 is, however,

. when the circuit becomes overloaded toanextent, such that arm ZGisheatedand flexed so asto A connected to 26 38 .of rivet 21 and bushing 32; and its other-,end

that rivet 21 c1amps bushing 32, element 36, and

the lower end of arm 26 to the base portion 01?,

member 12.

Bottom member' ljz is-provided at one side thereof with a slot 40 extending through the threaded 'tportion l6 thereof. The slot 40 is provides for re; taining a spring arm 42 on member 12. Arm 42-. has a corrugated end portion-l4 which seats ingslot g 40 and interfits with thc threaded portion ,|6. The thickness of the corrugated endportiondd. of arm 42 is slightly less than the depth'of slot 46 so that when the arm is seated in s1ot40 and 5 shell [8 arranged over member I2; a narrow paS.-- sage is provided between a corrugated portion 44 '3 and shell [8 which may befi lled, with 591C181? through an inlet 46 at the upper end of slot In so as to thereby solder arm, to shell [8 along their adjacent faces asat 41.

The free end of arm 42 extends through anopening 48v in the wall of member 12 and intochamber 22. 7 At its upper end arm 26 is shaped silver alloy which is relatively unaffected by the arcing which occurs when the, pointsopen and close the circuit.

On its upper face, cap I 4 is provided with a. recess 56 at the; center of whichthere isa hole. 58 extending from recess 56.into chamber 22;1- Within hole 58 there is slidably mountedabutton i.. member 66. The length of buttonfiil is somewhat greater than the thickness of map It and the but-,.-

ton is arra-ngedsuch that its lower end 62 engages the upper side of arm 42 at a point spaced-inwardly from contact point 56. At its upperend,

button 68 is provided with a head portion 64 which, when the button is in the depressed. position, seats in recess 56.

When arm 42 is engaged by the cinema] arm 25, head 64 of button ,60 is substantially...

flush with the top surfaceof cap 1 However,

disengage hook 52 from arm 42, arm 42 springs upwardly and shifts button 68 outwardly so that th ough a armament "Q 36 which has one end disposed between the heady;

its head 64 projects above the upper face of cap M as is shown in broken lines in Figure 1. When it is desired to reset the fuse after the circuit is broken, button 60 is simply depressed so that the lower end 62 thereof engages arm 42 and flexes it downwardly. If the resetting operation is performed after arm 26 has cooled sufficiently to assume its normal upright position, shown in solid lines, contact 56 engages contact 55 and flexes arm 26 outwardly to the dotted line position shown in Figure 1. When contact 56 passes beneath the lower end of contact 54, arm 26 springs back to its normal position where contact 56 is engaged beneath contact 54. Thereafter, if the circuit should become overloaded for some reason, arm 26 will become heated in proportion to the amount of overload in the circuit and will begin to flex outwardly out of engagement with arm 42. When the overloading conditions exceed the rating of the fuse, arm 26 will be flexed to a position wherein contact 54 disengages contact 56 and thus permits arm M to spring upwardly and push button 68 outwardly to the projected position.

It Will be noted that contacts 54 and 55 are shaped such as to prevent direct contact between arms 26 and 42, both when arm 42 is pushed downwardly into engagement with arm and when arm 26 becomes heated and flexed outwardly to disengage arm t2. Arm 2?: will, of course, be designed to flex a desired amount in accordance with the desired rating of the fuse. If the fuse is rated at amperes, the arm 28 will disengage arm 42 when the current in the circuit exceeds 30 amperes. provided as a safety feature and is designed to melt and break the circuit if for some reason arm 25 fails to function. Accordingly, element 36 is designed to burn out at a current value slightly above the rating of the fuse. If the fuse is rated at 30 amperes, element is designed to burn out at about 33 to 35 amperes.

In Figure 4 I have shown a modified construc tion for the contact points at the free ends of arms 26 and 42. In this arrangement the contact point 10 on arm 42 and the contact point F2 on the arm 2% are formed as two integrally connected half portions, the portion T4 being formed of a conducting material such as a nickel-silver alloy and the portion 16 being formed of a nonconducting material such as Bakelite or coldmolded rubber. Contact point 10 is fashioned with the conducting portion '14 forming the top half and with the non-conducting portion 16 forming the bottom half of the point. Contact 12 is fashioned with the conducting portion hi forming the bottom half and the non-conducting portion 78 forming the top half of the contact.

It will be noticed that with the arrangement illustrated in Figure l very little arcing occurs either when the circuit is broken or reset. When the circuit becomes overloaded to an extent such as to cause bimetallic arm 26 to flex to the position shown in broken lines, contact point Hi springs upwardly out of engagement with contact point 1'2. As soon as electrical contact between these points is broken, it will be noted that the non-conducting portions E6 of the contacts wipe past one another rather than the conducting portions 15. This action tends to substan-- h tially reduce the tendency for arcing between the contacts Hi and i2.

When the contacts are in the separated condition illustrated in broken lines and it is desired to reset the fuse, it will be noted that, as the Fusible element 36 is 4 contact 10 is depressed into engagement with contact 12, the most proximate portions of the two contacts are the insulating portions 16. Therefore, as the contacts approach one another, there is no tendency for arcing. As the contact 18 moves downwardly into engagement with contact 12, the non-conducting portion 16 of contact HI engages the non-conducting portion 16 of contact 12 and the circuit is established only when these portions wipe past one another so that the conducting portion T4 of contact 10 contacts the conducting portion 14 of contact 12.

It Will thus be seen that I have provided a very simply constructed circuit breaker for a plug-in fuse socket. The provision of the projectable button enables the user to determine at a glance which of several circuits in a fuse box has been opened through the operation of the circuit breaker. Moreover, the resetting operation is performed safely and quickly by merely depressing button 60, I

It will be noted that all of the electrical conducting members of the circuit breaker are inaccessible when the fuse is disposed within a fuse socket and there is no danger, therefore, of the user receiving a shock when he attempts to reset the fuse. This application is a continuation-in-part of my earlier application Serial No. 107,313, filed July 28, 1949, and now abandoned.

I claim:

1. A resettable circuit breaker comprising a shell adapted to be inserted into a conventional plug-in fuse socket, said shell forming a contact member, a body of insulation material circumferentially enclosed by said shell, said body having a substantially enclosed chamber therein, rivet means at the lower end of said body having a shank portion extending upwardly through the bottom Wall of said body and projecting into said chamber, said shank portion having a head at the inner end thereof, a disc of insulating material on said shank portion disposed between said head and the bottom wall of said body, a bimetallic arm extending upwardly in. said chamher and having its lower end bent laterally to project beneath said disc of insulation material, a, fusible member having one end thereof disposed between the lower face of said head and the upper face of said disc and having its other end projecting beneath the lower face of said disc, said head being arranged to clamp the lower end of said bimetallic arm and said other end of said fusible element in contacting relation between the lower face of said disc and the bottom wall of said body, said disc having a portion on the lower side thereof effectively insulating said clamped ends from the shank portion of said rivet means, a spring arm connected with said shell and projecting transversely through said chamber, said bimetallic arm having a free end thereof lying in the path of movement of the free end of said spring arm such that the free end of said spring arm is engageable with said bimetallic arm when said spring arm is flexed downwardly, and a push button slidably arranged in the top wall of said body and engageable with said spring arm for flexing said spring arm downwardly into engagement with the free end of said bimetallic arm.

2. A resettable circuit breaker comprising a shell adapted to be inserted into a conventional plug-in fuse socket, said shell forming a contact member, a body of insulation material circumferentially enclosed by said shell, said body having a substantially enclosed chamber therein, a

contact member at the lower end of said body extending upwardly into said chamber, a bimetallic arm in said chamber connected at one end to one of said contact members, a resilient arm in said chamber connected to the other of said contact members, said body having an aperture at the upper end thereof, a pin slidable in said aperture and having its inner end projecting into said chamber, said spring arm being biased to engage the inner end of said pin at a point spaced from the free end of said spring arm and shift said pin in said apertures so that the outer end of the pin projects above the outer surface portions of said body surrounding said aperture, said bimetallic arm in its normal position having a portion lying in the path of movement of the free end of said spring arm, said pin in the outwardly projected position being arranged to be depressed to interengage said spring and bimetallic arms to hold said spring arm in a flexed position and thereby permit said pin to remain in a depressed position, said spring and bimetallic arms having the free ends thereof imbedded in individual contact members, said last mentioned contact members comprising an electrical conducting portion and a non-conducting portion, said non-conducting portion comprising the upper portion of said contact member at the free end of said bimetallic arm and the lower portion of the contact member at the free end of said spring arm and said conducting portion comprising the lower portion of the contact member at the free end of said bimetallic arm and the upper portion of the contact member on said spring arm.

3. A resettable circuit breaker comprising a shell adapted to be inserted into a conventional plug-in fuse socket,rsaid shell forming a contact member, a body of insulation material circumferentially enclosed by said shell, said body having a substantially enclosed chamber therein, rivet means at the lower end of said body having a shank portion extending upwardly through the bottom wall of said body and projecting into said chamber, said shank portion having a head at the inner end thereof, a disc of insulating material on said shank portion disposed between said head and the bottom wall of said body, a bimetallic arm extending upwardly in said chamber and having its lower end bent laterally to project beneath said disc of insulation material, a fusible member having one end thereof disposed between the lower face of said head and the upper face of said disc and having its other end projecting beneath the lower face of said disc, said head being arranged to clamp the lower end of said bimetallic arm and said other end of said fusible element in contacting relation between the lower face of said disc and the bottom wall of said body, said clamped ends being spaced out of contact with the shank portion of said rivet means, a spring arm connected with said shell and projecting transversely through said chamber, said bimetallic arm having a free end thereof lying in the path of movement of the free end of said spring arm such that the free end of said spring arm is engageable with said bimetallic arm when said spring arm is flexed downwardly, and means extending through the wall of said body and engageable with said spring arm for flexing said spring arm into engagement with the free end of said bimetallic arm.

4. A resettable circuit breaker comprising a shell adapted to be inserted into a conventional plug-in fuse socket, said shell forming a contact member, a body of insulation material circumferentially enclosed by said shell, said body having a substantially enclosed chamber therein, rivet means at the lower end of said body having a shank portion extending upwardly through the bottom wall of said body and projecting into said chamber, said shank portion having a head at the inner end thereof, a disc of insulating material on said shank portion disposed between said head and the bottom wall of said body, a bimetallic arm extending upwardly in said chamber and having its lower end bent laterally to project beneath said disc of insulation material, a fusible element having one end thereof contacting said head of said rivet means and having its other end projecting beneath the lower face of said disc, said rivet means being arranged to clamp the lower end of said bimetallic arm and said other end of said fusible element in contacting relation between the lower face of the disc and the bottom wall of said body, the shank of said rivet means extending through said clamped ends but spaced out of contact therefrom, a spring arm connected with said shell and projecting transversely through said chamber, said bimetallic arm having a free end thereof lying in the path of movement of the free end of said spring arm such that the free end of said spring arm is engageable with said bimetallic arm when said spring arm is flexed downwardly, and a reset mechanism comprising a member extending through a wall of said body and engageable with said spring arm for flexing the spring arm into engagement with the free end of said bimetallic arm.

BEN MILLEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,431,220 Donle Oct. 10, 1922 1,889,488 OBrien Nov. 29, 1932 2,147,754 Rivers Feb. 21, 1939 2,458,804 Sundt Jan. 11, 1949 

